This invention relates to a heat generating apparatus which includes a wind turbine and a fluid pump device for forcing liquid through a discharge orifice and into a fluid reservoir. More particularly, this invention is concerned with an improved heat generating apparatus of the foregoing type wherein an accelerometer is employed in conjunction with the wind turbine and the discharge orifice to vary the size of the discharge orifice in relation to the speed and acceleration of rotation of the wind turbine so that the turbine operates at its optimum tip speed ratio in varying wind speeds.
Heat sources are needed which are decentralized in that they do not depend on the commercial utility grid for remote areas and for times when the grid is not reliable or when power from the grid becomes too expensive. Wind energy provides such a source. Wind energy is renewable and inexpensive; it does not increase pollution and does not contribute to the greenhouse effect. The wind system would be more efficient if heat is directly generated rather than converted from electricity generated from the wind. Typical uses might include residential space heating, hot water heating for direct use, industrial process heating, grain drying on farms or distillation of fresh water from seawater near oceans.
It has long been known, for example by those who work with hydraulic devices that hydraulic fluids become warmer after usage. A fluid forced through an orifice or slot will become heated. This phenomenon was used in John E. Knecht's "Wind Driven Heating System" as described in U.S. Pat. No. 4,366,779. The present invention is an improvement of Knecht's system to more efficiently extract power from the wind. The apparatus employed by Knecht was designed for a steady wind under the apparent assumption that it would work well in a range of variable winds and has a gear pump at the top of the tower. In contrast, the apparatus of this invention has the reservoir at ground level where it is unaffected by turbine rotation and reduces weight on the tower. Further the apparatus of this invention employs an accelerometer to measure the effect on the turbine of a variable wind and to adjust the discharge orifice thereby maximizing energy extraction from the wind.
A fixed orifice system of the general foregoing type was built at the Shimadzu Corporation of Kyoto, Japan. Their orifice does not respond to wind acceleration but does have a flow rate limiter to prevent the turbine from over-speeding. The orifice also has a wax actuated stop valve to close the orifice when the temperature becomes too high and so prevents overheating of the system. Their results were presented in "Windpowered Heat Generation Unit" by H. Fuji, Y. Kita and Y. Nomura at the Second ASME Wind Energy Symposium, Houston, Tex., Jan. 30th-Feb. 3, 1983.
In a paper presented at the Third ASME Wind Energy Symposium in New Orleans, La. on Feb. 14, 1984, K. Seki, Y. Shimizu and S. Narita of Tokai University, Kanagawa, Japan and entitled "A Study of Direct Heat Exchange System for Straight Blade Non-Articulated Vertical Axis Wind Turbine" a system of the type concerned with in this invention was described which also has a fixied orifice. A computer was employed to electronically control the load on a straight blade vertical axis turbine in response to changes sensed in wind speed. The electronics in the described system make it expensive and no measurement of the ratio of the angular acceleration to angular velocity squared of the shaft was presented.
It is an advantage of this invention to provide an apparatus for producing heat from a renewable energy source wherein a self-governing device extracts the optimal power possible from the wind for a given turbine and converts most of the energy extracted from the wind into heat by assuring that the friction in the system is converted to useful heat.
Another advantage of this invention is to provide heat from the wind by purely mechanical means so that the system is useful in remote areas and results in a cost savings by being independent from the utility system as well as to provide a simple mechanical system which may be easily repaired by a user with few technical skills.
A still further advantage is the control of a wind turbine so that it operates at its optimal tip speed ratio by matching the heat converter to any given wind turbine by the proper accelerometer to orifice linkage, pressurizer gear size, and adjustable orifice size.
Yet another advantage of the invention is an apparatus of the following type which can be used for many heating applications including residential, farming or industrial. For example: on farms it can be used for grain drying; in warm arid regions it can be used in a water distillation system to provide pure water; and in cold regions it can replace or supplement space heating or hot water heating now done by combustion or electrical means.